1. Field of the Invention
The invention relates to a frame stave for a heddle frame, including a supporting bar structured as a rectangular hollow body having two broad sides and two narrow sides, and including a heddle carrying rod extending at a distance from and parallel to one of the narrow sides, which heddle carrying rod is rigidly mounted to the supporting bar via a supporting member.
2. Description of the Prior Art
Generally known designs of heddle frames which consisted respectively of frame staves which are interconnected by side supports included frame staves consisting of light-metal hollow profiles at which the respective heddle carrying rod is formed thereonto in an integral manner. Because, however, today's weaving machines are to operate at continuously higher speeds and the longer the broader weaving machines are produced, the limits of the ability to take up loads of the extremely fast oscillatingly moved heddle frames are reached of which the frame staves which consist of light-metal profiles do not posess a sufficient alternating bending strength. Because the alternating bending strength of steel is substantially higher than that of light-metal it has also been proposed to use frame staves made of steel specifically for broad heddle frames in weaving machines operating at high speeds. These frame staves designed as a sandwich structure have, in order to reduce the weight quite thin-walled sheet metal parts at the broad sides and thicker longitudinal profiles at the narrow sides of a supporting bar which forms a hollow body and which, furthermore, carries the parallel extending heddle carrying rod at a metal connecting part.
Such a frame stave as disclosed in U.S. Pat. No. 4,901,767, commonly owned herewith, has a plurality of specifically flat and not deformed single parts which are assembled to a frame stave by a corresponding number of welding seams. This design has, however, various drawbacks. It is not only that to many welding seams are needed which renders to production more expensive whereby the necessary precision regarding the straightness of the frame stave to be produced can only be reached with difficulties because of the large number of welding seams, but also the thickness of the material of the thicker sheet metal parts which form the narrow sides of the supporting bar is not sufficient to guarantee a high alternating bending strength of the structure. Due to the oscillations when operating the heddle frame in the weaving machine the frame stave causes the generation of sound waves, but the sound attenuating effect of the foamed body which is contained in the hollow space of the supporting bar is minimal only.